U.S. patent application number 10/996052 was filed with the patent office on 2005-06-02 for rotating shaft coupling.
Invention is credited to Hirano, Izuho, Kaneko, Kaoru, Miyagi, Yoshiyuki, Mizuno, Yuichiro, Tokuoka, Takamitsu.
Application Number | 20050119055 10/996052 |
Document ID | / |
Family ID | 34616608 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050119055 |
Kind Code |
A1 |
Tokuoka, Takamitsu ; et
al. |
June 2, 2005 |
Rotating shaft coupling
Abstract
Out of combinations of three pins(15) and bushes(16a-16c), a
clearance between one of the bushes(16a) and the pin(15) is small,
and a clearance between the other two bushes(16b,16c) and the
pins(15) are large, whereby torque transmission is always performed
by only one pin(15) and the bush(16a) during rotation to avoid a
transfer phenomenon between the pins. Disposing the pins and the
bushes at an equal interval allows a good balance of rotation to
provide an easy assembly.
Inventors: |
Tokuoka, Takamitsu;
(Yokohama-shi, JP) ; Hirano, Izuho; (Yokohama-shi,
JP) ; Miyagi, Yoshiyuki; (Tokyo, JP) ; Kaneko,
Kaoru; (Tokyo, JP) ; Mizuno, Yuichiro; (Tokyo,
JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Family ID: |
34616608 |
Appl. No.: |
10/996052 |
Filed: |
November 24, 2004 |
Current U.S.
Class: |
464/137 |
Current CPC
Class: |
F16D 3/48 20130101 |
Class at
Publication: |
464/137 |
International
Class: |
F16D 003/48 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2003 |
JP |
2003-399450 |
Claims
What is claimed is:
1. A rotating shaft coupling which connects a first shaft and a
second shaft arranged co-axially with each other, comprises: a
first rotating body disposed to one of the first and the second
shaft; a second rotating body disposed to the other, as opposed to
the first rotating body; a plurality of pins spaced by an interval
of an equal angle on a circumference of the first rotating body at
a predetermined radius away from a shaft center thereof, the pins
extending in a shaft direction and having the same diameter with
each other; and a plurality of engagement sections at locations in
the second rotating body corresponding to the pins to receive the
pins, wherein: a first allowance is arranged between an inner
surface of one of the engagement sections and a pin engaged with
the one, the first allowance corresponding to a deviation amount
assumed between a shaft center of the first shaft and a shaft
center of the second shaft, and a second allowance is arranged
between an inner surface of the other of the engagement sections
and the pin engaged with the other, the second allowance being
larger than the first allowance.
2. The rotating shaft coupling according to claim 1, wherein: the
engagement section having the first allowance includes a
cylindrical bush permitting the first allowance and having
cushioning function.
3. The rotating shaft coupling according to claim 2, wherein: the
bush is inserted into a bore formed in the second rotating body,
and a O-ring made of an elastic body is interposed in a circular
clearance formed between the bush and the pin.
4. The rotating shaft coupling according to claim 2, wherein: the
bush is inserted into a bore formed in the second rotating body,
and a O-ring made of an elastic body is interposed in a circular
clearance formed between the bush and an inner surface of the
bore.
5. The rotating shaft coupling according to claim 2, wherein: the
bush is made of a plastic material.
6. The rotating shaft coupling according to claim 1, wherein: the
pin and the bush are disposed at three locations by an interval of
120.degree. respectively in the first shaft and the second shaft,
and are placed on the same circumference from each shaft center of
the first shaft and the second shaft.
7. The rotating shaft coupling according to claim 1, wherein: the
first shaft includes a motor shaft of an electric motor, and the
second shaft includes an input rotor shaft of a compressor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotating shaft coupling
that transmits rotation between two shafts arranged as opposed to
each other.
[0003] 2. The Related Art of the Invention
[0004] As shown in Japanese Patent Publication No. 2001-289051A,
there is known a rotating shaft coupling that transmits rotation
between two shafts arranged on a same center line as opposed to
each other. A rotating body equipped with a plurality of pins is
mounted to one of a drive shaft or a driven shaft and a rotating
body equipped with a plurality of bushes engaged with the plurality
of the pins is mounted to the other, wherein a rotational torque is
transmitted from the drive shaft to the driven shaft through the
pins and the bushes engaged with each other.
SUMMARY OF THE INVENTION
[0005] An allowance (clearance) is disposed between the pin and the
bush in order to compensate for a deviation between each shaft
center of the two shafts. Therefore, in the event that there exists
the deviation with regard to each shaft center of the two shafts,
there occurs a transfer phenomenon that a location where the pin
and the bush are contacted to carry out torque transmission between
the two shafts in turn transfers with rotation of the two
shafts.
[0006] This phenomenon will be explained with reference to FIG.
1.
[0007] FIG. 1 shows a coupling mechanism which comprises a first
rotating body P provided with three pins (A), (B), and (C) spaced
at an angle of 120.degree. and a second rotating body Q provided
with three bushes (a), (b), and (c) at three locations
corresponding to the three pins, wherein rotation is transmitted
between the first rotating body P and the second rotating body
Q.
[0008] A spatial clearance or a circular allowance formed of an
elastic body as a bush is arranged between each pin (A)-(C) and
each bush (a)-(c). Each clearance is formed uniformly. In the case
of transmitting rotation from the first rotating body P to the
second rotating body Q, when one shaft center exactly corresponds
to the other, the respective pins (A)-(C) equally contact the inner
surfaces of the corresponding bushes (a)-(c), so that the torque
transmission is carried out at the three locations.
[0009] In contrast, in the event that, as shown in FIG. 1, the two
shafts are not co-axial by an eccentricity amount .DELTA.1, the
toque transmission is carried out at two locations of the pin (B)
and the pin (C) as shown in FIG. 1 (1). The pin (A) is not
contacted with the bush (a), to produce a free state where the
torque is not transmitted between the two shafts. FIG. 1-(2) shows
the state when the shafts have rotated in the counter-clockwise
direction by 90.degree. from the state in FIG. 1-(1). Then the pin
(A) contacts the bush a to start the torque transmission together
with the pin (B) where a clearance occurs between the pin (C) and
the bush (c). At a state in FIG. 1-(3) when the shafts further
rotate by 90.degree. from the state in FIG. 1-(2), the torque
transmission is carried out only by the pin (A) and at a state in
FIG. 1-(4) when the shafts further rotate by 90.degree. from the
state in FIG. 1-(3), the torque transmission is carried out by the
pin (A) and the pin (C). While the shafts thus rotate by one
rotation, a contact portion between the plurality of the pins and
the corresponding bushes transfers from one to the other in turn.
This transfer phenomenon causes occurrence of vibrations during
rotation transmission between the two shafts arranged as opposed to
each other. This problem is noticeable in case where an instrument
to generate torque fluctuations, such as a compressor is disposed
to a driven side to which the rotation is transmitted. When the
compressor is driven through the rotating shaft coupling, the
torque fluctuations of the compressor and the vibrations of the
coupling resonate to possibly generate larger vibrations and
noises.
[0010] In view of the above, there exists a need for a rotating
shaft coupling which overcomes the above-mentioned problems in the
related art. The present invention addresses this need in the
related art as well as other needs, which will become apparent to
those skilled in the art from this disclosure.
[0011] It is an object of the present invention to provide a
rotating shaft coupling, which can restrict generation of
vibrations and noises.
[0012] According to one aspect of the present invention, a rotating
shaft coupling which connects a first shaft and a second shaft
arranged co-axially with each other, comprises, a first rotating
body disposed to one of the first and the second shaft, a second
rotating body disposed to the other, as opposed to the first
rotating body, a plurality of pins spaced by an interval of an
equal angle on a circumference of the first rotating body at a
predetermined radius away from a shaft center thereof, the pins
extending in a shaft direction and having the same diameter with
each other, a plurality of engagement sections arranged at
locations in the second rotating body corresponding to the pins to
receive the pins, wherein: a first allowance is arranged between an
inner diameter of one of the engagement sections and a pin engaged
with the one, the first allowance corresponding to a deviation
amount assumed between a shaft center of the first shaft and a
shaft center of the second shaft, and a second allowance is
arranged between an inner diameter of the other of the engagement
sections and the pin engaged with the other, the second allowance
being larger than the first allowance.
[0013] These and other objects, features, aspects and advantages of
the present invention will be become apparent to those skilled in
the art from the following detailed description, which, taken in
conjunction with the annexed drawings, discloses preferred
embodiments of the present invention.
BRIEF EXPLANATION OF THE DRAWINGS
[0014] Referring now to the attached drawings which form a part of
this original disclosure:
[0015] FIG. 1 is an explanatory view showing a transfer phenomenon
with regard to torque transmission portions;
[0016] FIG. 2 is a front view showing a first preferred embodiment
according to the present invention;
[0017] FIG. 3 is a cross sectional view taken on lines A-A in FIG.
2;
[0018] FIG. 4 is a cross sectional view taken on lines B-B in FIG.
2;
[0019] FIG. 5 is a cross sectional view showing a second preferred
embodiment according to the present invention, corresponding to
FIG. 4;
[0020] FIG. 6 is a longitudinal sectional view showing a third
preferred embodiment according to the present invention;
[0021] FIG. 7 is a longitudinal sectional view showing a fourth
preferred embodiment according to the present invention; and
[0022] FIG. 8 is a longitudinal sectional view showing a schematic
construction in a fifth preferred embodiment according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] Selected embodiments of the present invention will now be
explained with reference to the drawings. It will be apparent to
those skilled in the art from this disclosure that the following
description of the embodiments of the present invention is provided
for illustration only, and not for the purpose of limiting the
invention as defined by the appended claims and their
equivalents.
[0024] FIG. 1-FIG. 4 show a first preferred embodiment. A drive
shaft 11 and a driven shaft 12 are arranged as opposed to each
other so that shaft centers of the drive shaft 11 and the driven
shaft 12 are on a co-axial line. Disc-shaped rotating bodies 13, 14
are disposed as opposed to each other to a shaft end of each of the
drive shaft 11 and the driven shaft 12. The drive rotating body 13
is provided at an end surface with three pins 15 inserted therein
and spaced by an equal interval of 120.degree. on the same
circumference at a predetermined radius away from a shaft center of
the rotating body 13 where the pins is placed in a shaft direction
of the drive shaft 11, as well as placed as opposed to the rotating
body 14.
[0025] The driven rotating body 14 is provided at an end surface
with bores 14a, 14b, and 14c formed at three locations
corresponding to the three pins 15. Namely a center of each bore
14a-14c is on the same circumference with the pins 15 and is placed
by an interval of 120.degree..
[0026] An inner diameter of each bore 14a-14c is the same with each
other and is larger than an outer diameter of each pin 15. A first
bush 16a is inserted in one bore 14a of the three bores 14a-14c and
the other two, namely the second and third bushes 16b, 16c are
inserted respectively in the other two bores 14b, 14c.
[0027] Each bush 16a-16c is formed in a cylindrical shape having a
through hole in a center thereof and made of a flexible plastic
material having lubricating property and cushioning property.
[0028] As shown in FIG. 3, the first bush 16a is press fitted in
the bore 14a, but has such an allowance to the pin 15 as to be
rotatable relative to the pin 15. In this case a deviation between
a shaft center of the drive shaft 11 and a shaft center of the
driven shaft 12, namely the eccentricity of the two shafts is
compensated by an allowance of the elastic deformation of the bush
16a. Accordingly the allowance is usually set based upon the
maximum eccentricity amount assumed between the drive shaft 11 and
the driven shaft 12.
[0029] The other two, the second and the third bushes 16b, 16c are
press fitted to the bores 14b, 14c. However, as shown in FIG. 4, an
inner diameter of each bush 16b, 16c is larger than an outer
diameter of the pin 15 and an allowance is disposed as a circular
clearance between an inner surface of each bush and an outer
surface of the pin 15. Namely the second bush 16b and the third
bush 16c have the same inner diameter with each other and the inner
diameter thereof is larger than that of the first bush 16a.
[0030] However, in FIG. 5 which is a second preferred embodiment,
an inner diameter of each bush 16b, 16c has the same with that of
the bush 16a and is fitted in the pin 15 without any clearance, but
an outer diameter thereof may be formed smaller to provide a
clearance between the each bush 16b, 16c and an inner surface of
each bore 14b, 14c.
[0031] Namely a first engagement section equipped with the first
bush 16a to receive the pin 15 has an allowance to compensate for
the deviation between the shaft center of the drive shaft 11 and
the shaft center of the driven shaft 12 and on the other hand, the
second and the third engagement section equipped with the second
and the third bush 16b, 16c have a second allowance to the pin 15,
the second allowance being larger than the first allowance.
[0032] As constructed above, when the rotation is transmitted from
the drive shaft 11 and the driven shaft 12, a larger clearance,
namely a larger allowance exists between the bushes 16b, 16c and
the pin 15 than between the bush 16a and the pin 15 out of the
combinations of the pins 15 at the three locations and the bushes
16a-16c. Accordingly, whether or not the deviation between the
shaft center of the drive shaft 11 and the shaft center of the
driven shaft 12 exists, torque of the drive shaft 11 is always
transmitted by only the pin 15 engaged with the bush 16a out of the
three pins 15.
[0033] Even if the bush 16a gets in contact with the pin 15, a
non-contact condition is maintained between the other two bushes
16b, 16c and the pins 15 or the bores 14b, 14c, and the rotational
torque is transmitted exclusively by one pin 15 from the drive
shaft 11 to the driven shaft 12.
[0034] Therefore, the phenomenon that one pin to perform the torque
transmission transfers to the other in turn during transmitting the
rotational torque as the conventional art disappears, to avoid
generation of vibrations due to what is called a transfer
phenomenon.
[0035] The three pins 15 and the three bushes 16a-16c are disposed
on the same circumference by an interval of an equal angle
respectively to the rotating body 13 and the rotating body 14 and
accordingly the rotating balance is maintained to be better, as
compared to disposition of one pin and one bush. And just in case
one pin 15 to perform the torque transmission is damaged, the other
two pins 15 can perform the torque transmission, to ensure a
failsafe function. And since any combination at three locations
between the three pins 15 and three bushes 16a-16c can be made, a
specific positioning of the pins and the bushes is not required on
assembly, to provide an easy assembly.
[0036] FIG. 6 and FIG. 7 show other preferred embodiments of the
present invention.
[0037] FIG. 6 is a longitudinal cross sectional view showing a
third preferred embodiment of the present invention where a
circular clearance is formed between the inner surface of the first
bush 16a and the outer surface of the pin 15 and an O-ring made of
an elastic body such as a rubber is interposed in the circular
clearance.
[0038] And FIG. 7 is a longitudinal cross sectional view showing a
fourth preferred embodiment of the present invention where a
circular clearance is formed between the outer surface of the first
bush 16a and the inner surface of the bore 14a, and an O-ring 17b
made of an elastic body such as a rubber is interposed in the
circular clearance.
[0039] According to the third and fourth preferred embodiments, a
relative displacement in a radius direction is ensured to be
larger, thereby to compensate, by the O-ring 17a or 17b, for
deformation of the bush 16a or the pin 15 due to a temperature
change or the like. And the eccentricity between the drive shaft 11
and the driven shaft 12 can be compensated only by the O-ring 17a
or 17b. As a result in these cases, a material having a small
deformation amount, for example a hard resin or a metal can be used
as the bush 16a.
[0040] FIG. 8 is a fifth preferred embodiment of a
compressor-driving apparatus to which a rotating shaft coupling of
the present invention is applied. Components structurally identical
to those in FIGS. 2-5 are referred to as identical numerals. In
FIG. 8, there are provided an air compressor 21 and an electric
motor 22 to drive the compressor 21. The compressor 21 is provided
with two rotors 23, 24 located in parallel. The rotor 23 is a male
rotor having spiral crown sections on a periphery thereof, and the
rotor 24 is a female rotor having spiral root sections
corresponding to the crown sections of the male rotor 23.
[0041] The rotor 23 and the rotor 24 are rotatably supported
respectively through a rotor shaft 25a and a rotor shaft 25b in a
housing 26 to be engaged through a slight clearance with each
other. In order to synchronously rotate the rotors 23, 24 in
opposing directions with each other, a gear 27a and a gear 27b to
be mutually engaged are mounted to the shaft 25a and the shaft
25b.
[0042] The electric motor 22 is received in a casing 28. And a
disc-shaped rotating plate 32 is mounted to an end of a motor shaft
31 of the electric motor 22. The housing 26 and the housing 28 are
fastened by bolts or the like (not shown) so that the rotor shaft
25b and the motor shaft 31 are positioned to be co-axial with each
other.
[0043] A plurality of pins 15 are disposed and inserted in a shaft
direction in a rotating plate 32 disposed in an end of the motor
shaft 31, and are placed as opposed to the gear 27b. On the other
hand, plastic bushes 16a-16c engaged with the pins 15 are disposed
at locations to the gear. 27b corresponding to the pins 15. Under
the housing 26 and the housing 28 coupled, the pins 15 are engaged
with the bushes 16a-16c, to transmit a rotational force of the
drive shaft 11 to the rotor shaft 25b and to rotate the compressor
21.
[0044] In a relation with the rotating shaft couplings shown in
FIGS. 2-7, the motor shaft 31, the motor shaft 25b, the rotating
plate 32, and the gear 27b correspond respectively to the drive
shaft 11, the driven shaft 12, the drive rotating body 13, and the
driven rotating body 14, which constitutes the rotating shaft
coupling in the same as the other preferred embodiments to perform
the rotation transmission only at one location out of the
combinations between the plurality of the pins 15 and the bushes
16a-16c.
[0045] Namely only the first bush 16a and the pin 15 transmit the
rotational torque between the shafts. Thereby, when the electric
motor 22 rotates the compressor 21, the rotating shaft coupling
prevents occurrence of vibrations or resonance, and noises due to
the transfer phenomenon of the pins 15 in the rotating shaft
coupling, and as a result, a quiet driving by the electric motor 22
can be performed.
[0046] While only selected embodiments has been chosen to
illustrate the present invention, it will be apparent to those
skilled in the art from this disclosure that various changes and
modifications can be made herein without departing from the scope
of the invention as defined in the appended claims. Furthermore,
the foregoing description of the embodiments according to the
present invention is provided for illustration only, and not for
the purpose of limiting the invention as defined by the appended
claims and their equivalents. The contents of Japanese Patent
Application No. 2003-399450 (filed 28 Oct. 2004) is incorporated
herein by reference.
* * * * *